Field of the Invention
The present invention relates to an electric discharge machine having a rotary table.
Description of the Related Art
FIG. 6 is a view illustrating a conventional rotary table structure used in an electric discharge machine or the like.
As shown in FIG. 6, a power unit 2 and a speed reduction unit 3 are disposed in a rotary table body 1. A bearing support section 7 is attached to the distal end side of the rotary table body 1, and a bearing section 4 is supported by the bearing support section 7. A shaft 5 and a faceplate 6 are secured to the opposite sides of the bearing section 4, and they can freely rotate in synchronism with the rotation of the speed reduction unit 3. A sealing mechanism section 8 is provided in the vicinity of the bearing support section 7, and sealing members 9 are arranged in the sealing mechanism section 8. The sealing members 9 are configured to contact the outer peripheral surface of the faceplate 6, thereby preventing a working fluid from intruding the rotary table body 1 through a gap 13 between the sealing mechanism section 8 and the faceplate 6.
During machining by means of the electric discharge machine, chips or sludge is produced and suspended in the working fluid. If the sludge adheres to the sealing mechanism section 8, it causes early wear of the sealing members 9, so that a rotary table with an air-seal structure has been proposed to overcome this problem (Japanese Patent Application Laid-Open No. 2011-104725).
While the sealing members 9, which are consumables, require periodic replacement, their life greatly depends on the operating conditions, working hours, and the frequency of daily cleaning. Thus, the replacement time for the sealing members 9 is not specifically determined, and an operator is expected to periodically replace the sealing members 9, based on visual inspection or preventive maintenance.
If the operator fails to inspect the sealing members 9, therefore, the working fluid may intrude the rotary table body 1, thereby damaging important components, including the power unit 2 and the speed reduction unit 3, in the rotary table.